textproduct: Albany

WHAT HAS CHANGED

Slight and low chance PoPs were expanded further in the west/southeast Adirondacks and eastern Catskills this afternoon for pop-up/pulse showers/t-storms.

Coverage of showers-thunderstorms was kept in the 25-50% range for Mon pm-early evening ahead of the initial disturbance with some likely PoPs (55-65%) over the southern Dacks and eastern Catskills.

KEY MESSAGES

1) Mainly dry conditions with seasonable temperatures and low humidity levels for today, except few showers/thunderstorms west of Hudson River Valley.

2) Moderate to high confidence for periods of rain showers/rain and a chance of thunderstorms late Mon into Thu across eastern NY and western New England due to a slow moving low pressure system.

DISCUSSION

KEY MESSAGE 1...

High pressure continues to move east of Nova Scotia this morning with temps cooling into the 50s to lower 60s with some patchy fog north/northeast of the Capital Region, where the skies are mainly clear with calm winds. A mid and upper level trough will move over the region today with some diurnally driven pop-up showers/thunderstorms over the southwest Adirondacks, eastern Catskills and the western Mohawk Valley. The mean MUCAPEs on the HREFs are 250-750 J/kg with very little deep shear of less than 15 KT. Pulse-type thunderstorms may occur with brief downpours. Severe weather is not expected due to limited instability and shear. Dewpoints will be in the 50s and enough subsidence from weak ridging downstream over the Canadian Maritimes will keep most of the region dry with humidity levels fairly comfortable. Max temps will be seasonable with 80-85F readings in the valleys and mainly 70s over the hills and mtns. The isolated-widely scattered showers should diminish quickly with the loss of the diurnal heating. The skies will become partly cloudy/mostly clear with light to calm winds with some patchy fog developing north and west of Albany especially where any rain occurs. Lows will be milder in the 50s to lower 60s.

KEY MESSAGE 2...

The weather pattern becomes very active Mon thru the mid week with a potential late July moderate-heavy rain event/rainstorm Tue-Thu. Initially, a lead short-wave and a warm front associated with a low pressure system moving into the west- central Great Lakes Region will bring some scattered showers and thunderstorms to the forecast area Mon-Mon night. The mid and upper level trough becomes more established over NY and New England. Clouds increase and dewpoints rise into the 60s. SBCAPEs increase into the 250-1000 J/kg range with very weak shear again less than 20 KT. Mid level lapse rates look weak. The shower/thunderstorm coverage will likely increase initially over and near the higher terrain and then spread eastward over the valleys slowly. The lack of shear will limit thunderstorms organization and limit any severe threat. We tried to keep PoPs in chance range 25-54% with some likely values over the southwest Dacks and eastern Catskills. General Thunder from SPC for Day 2 looks right based on the limited instability and weak shear. Max temps look similar to Sun with seasonable readings in the mid 70s to mid 80s over the region. The shower and thunderstorms activity should diminish once again overnight with milder temps in the mid 50s to mid 60s.

An impactful weather system looks to move into eastern NY and western New England Tue into Thu. A strong short-wave trough digs into the lower Great Lakes Region and Ohio Valley. Low and mid level heights fall 2-3 STDEVs below normal. A primary low pressure system moves over western NY and PA Tue pm with rain beginning to over spreading the region with showers and some thunderstorms. The EC continues to be further north holding the primary Tue night into Wed with secondary low forming over southeast PA and NJ. The GFS/CMC and several ensembles members are further south and east with the secondary forming over northern VA or the Delmarva Region which would bring moderate- heavy rain into the region late Tue night thru Wed as the wave moves northeast, and would perhaps limit the heavy rain to locations south and east of the Capital Region. PWATs do increase to 1.50" or so, and the NAEFS PWAT anomalies are +1-2 STDEVs above normal. The 500 hPA low closes off over or near eastern NY and western New England, which slows the sfc cyclone down which will be tapping Atlantic and Gulf moisture. The latest 01Z/26 NBM 48-hr probabilities > 1" of rain ending 12Z/Thu are 65-85% across the region; >2" probabilities for the same time frame are 35-70% greatest south and east of the southern Dacks and the >3" probabilities are 30-50% from roughly the Capital District south and east. A widespread 1.5-4" rainfall (some locally higher amounts over the eastern Catskills) over a 36-48 hr time frame are possible, but the QPF continues to vary quite a bit with the guidance.

Locations to the south and east of the Capital District could receive the highest amounts and if confidence increases later in time some locations could need a Flood Watch due to training convection or slow moving rainbands causing poor drainage and urban flooding or isolated to spotty scattered flash flooding. WPC has issued a 'Slight Risk' for scattered instances of flash flooding from Albany south and east over the eastern Catskills, mid Hudson Valley, southern Taconics, southern Berkshires and NW CT and a 'Marginal Risk' for isolated instances for potential flash flooding in the newly updated Day 3 Excessive Rainfall Outlook /ERO/ for Tue-Tue night. The Day 4 ERO has the entire area in a 'Slight Risk' for Wed-Wed night, except for the southern Dacks, western Mohawk Valley and the Lake George Region. Dry antecedent conditions heading into this event, high gridded FFG values and limited rainfall from the Capital Region north and east over the past 2 weeks should limit hydro concerns. We will have to monitor for any training convection, which will enhance hydro concerns, for some locations this could be a good soaking rainfall over a couple of days. The rainfall may continue in the deformation zones of the slow moving wave and cut-off low Wed into Thu morning. Temps tends cooler than normal Tue into Wed with 70s and some 60s over the higher terrain. Showers should begin to diminish Thu with a drier air mass settling in late in the week with seasonable temps.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Through 12Z/Monday, mainly VFR conditions are expected to prevail through the 24 hour TAF period. Some low clouds/fog at KPSF should lift by 13Z/Sun. There is a slight chance (10-20%) of some patchy fog developing late tonight (after 07Z/Mon) at KGFL. Light/variable winds will become south to southeast at 4-8 KT this afternoon, then becoming light/variable once again after sunset this evening.

Outlook...

Monday Night: Low Operational Impact. Slight Chance of SHRA...TSRA. Tuesday: High Operational Impact. Definite SHRA...Chance TSRA. Tuesday Night: High Operational Impact. Definite SHRA...Chance TSRA. Wednesday: High Operational Impact. Definite SHRA...Chance TSRA. Wednesday Night: High Operational Impact. Likely SHRA...Slight Chance TSRA. Thursday: High Operational Impact. Likely SHRA...Chance TSRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.